Analysis of Malodorous Substances of Human Feces

Various malodorous substances generated from human feces were analyzed immediately after the use of a Western-style toilet by 50 subjects. The types and amounts of these malodorous components varied slightly between individuals, depending on the food that they had eaten and their state of health. Hydrogen sulfide was detected at concentrations of 5-26 ppb, methyl mercaptan at 2-15 ppb, ammonia at less than 100 ppb, propylaldehyde, fatty acids, and pyridine at about 10 ppb, and trimethylamine at around trace levels. When subjects had diarrhea, the amounts of fatty acids, particularly acetic acid, in feces were more than 100000-fold higher than in feces of those in normal health.